How are flange bolts tightened?
Tightening sequence. The first pass, lightly tighten the first bolt then move directly across or 180 degrees for the second bolt, then move1/4 turn around the circle or 90 degrees for the third bolt and directly across for the fourth. Continue this sequence until all bolts are tightened.
What kind of bolts are used on flanges?
The most common materials for stud bolts (for flanges) are ASTM A193 (grade B7, B8, B8M, B8T), ASTM A453 (grade 660), ASTM A320 (grade L7, L7M), and ASTM A182 (duplex and super duplex bolting).
What are four methods of torquing?
Use of tension indicating methods.
- Torque Control Tightening. Controlling the torque which a fastener is tightened to is the most popular means of controlling preload.
- Bolt Stretch Method. A problem relating to the tightening of large bolts is that very high tightening torques are required.
- Heat Tightening.
What is a bolt tightening sequence?
Bolt tightening sequences are when an arrange of bolts are tightened in a pattern to the required torque. The sequence the bolts are tightened is a symmetrical pattern to reduce the amount of pre-load lost in a bolt, as a result of elastic interactions. Torque is normally applied to a bolt using a torque wrench.
What is Hydraulic bolt tensioning?
A hydraulic bolt tensioning tool provides a quick and easy method for tightening large diameter bolts to high and accurate pre-loads. Unlike conventional methods it does not use torque and does not require any forceful turning of the nut or bolt, like impact wrenches, flogging spanners or hydraulic torque wrenches.
What is the bolt method?
This bolt tightening method involves measuring bolt tension through things such as load indicating bolts and washers, along with techniques that calculate the length change of fasteners.
What is the torque loading of flange bolts?
Torque is the turning force measured in Newton metre (Nm) applied to tighten (turn) the nut on a bolt. In a bolted flange, the applied torque generates the axial load in the bolt. The bolt acts like a spring. Tightening the nut stretches the bolt, which increases the load on the gasket.
What tool is used to tighten bolts?
wrench
wrench, also called spanner, tool, usually operated by hand, for tightening bolts and nuts.
Is standard for flange bolt?
ISO 4162 Flange Bolts are regular hex head bolts with built-in washer and externally threaded body. It comes with plain or serrated flange configuration. ……ISO 4162 M8 Flange Bolt.
| Nominal Diameter | M8 |
|---|---|
| P Pitch b L≤125 125＜L≤200 L＞200 dc max ds max min e min k max s max min | 1.25 22 28 – 17 8 7.78 10.8 8.5 10 9.64 |
How are flange bolts measured?
To measure the diameter of screws and bolts, you measure the distance from the outer thread on one side to the outer thread on the other side. This is called the major diameter and will usually be the proper size of the bolt.
Why bolt tightening in flange joints is important?
Bolted flange joints are used widely in water mains. It is the reason why a proper bolt tightening sequence in flanged joints is a must. This precaution helps in controlling the stress variation in flange joint components. If not done right, the chances of leakage are higher at flanged pipe joints during the operating conditions.
What happens to the bolt when tensioned?
When bolt tensioning, the bolt is preloaded and stretched during the process. When this has been completed correctly, with the nut tightened and the tensioner load removed, the bolt will automatically want to return to its original length.
How do you tighten a 7/8 bolt?
All stud bolts of 7/8″ and above shall be tightened using a torque wrench. While tightening the bolt with torque wrenches (for pipe / Manway flanges) ensure that tightening load to each bolt is applied as uniformly as possible. The tightening shall be carried out in three or four stages in steps of 30, 50 & 70 percent of the final torque value.
How to use torque wrenches to tighten the bolts?
While tightening the bolt with torque wrenches (for pipe / Manway flanges) ensure that tightening load to each bolt is applied as uniformly as possible. The tightening shall be carried out in three or four stages in steps of 30, 50 & 70 percent of the final torque value. A fourth stage again uses 70 percent of the final torque value.